No matter if it's royal purple or ford recommended Always use full synthetic. Yes it means that you can go 7,000 miles without changing, but i still change mine before that plus full synthetic is cleaner and performs better than the average leading oil. Full Synthetic is the way to go and you can also help it by adding Z max to your oil and fuel. I personally use this in my car and in my dads cobra as well and if that doesn't comfort you, SHELBY uses this product and also recommended it, which is why we use it. Good luck on the learning process and just to let you know, you never stop learning. Ask anyone!

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